Method for thin film deposition using multi-tray film precursor evaporation system

ABSTRACT

A method for depositing a Ru metal layer on a patterned substrate from a film precursor vapor delivered from a multi-tray film precursor evaporation system. The method comprises providing a patterned substrate in a process chamber of a deposition system, and forming a process gas containing Ru 3 (CO) 12  precursor vapor and a carrier gas comprising CO gas. The process gas is formed by: providing a solid Ru 3 (CO) 12  precursor in a plurality of spaced trays within a precursor evaporation system, wherein each tray is configured to support the solid precursor and wherein the plurality of spaced trays collectively provide a plurality of surfaces of solid precursor; heating the solid precursor in the plurality of spaced trays in the precursor evaporation system to a temperature greater than about 60° C. and maintaining the solid precursor at the temperature to form the vapor; and flowing the carrier gas in contact with the plurality of surfaces of the solid precursor during the heating to capture Ru 3 (CO) 12  precursor vapor in the carrier gas as the vapor is being formed at the plurality of surfaces. The method further includes transporting the process gas from the precursor evaporation system to the process chamber and exposing the patterned substrate to the process gas to deposit a Ru metal layer on the patterned substrate by a thermal CVD.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 10/998,420 entitled “MULTI-TRAY FILM PRECURSOR EVAPORATIONSYSTEM AND THIN FILM DEPOSITION SYSTEM INCORPORATING SAME,” filed onNov. 29, 2004, the content of which is hereby incorporated by referenceherein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a system for thin film deposition, andmore particularly to a system for evaporating a film precursor anddelivering the vapor to a deposition chamber.

2. Description of Related Art

The introduction of copper (Cu) metal into multilayer metallizationschemes for manufacturing integrated circuits can necessitate the use ofdiffusion barriers/liners to promote adhesion and growth of the Culayers and to prevent diffusion of Cu into the dielectric materials.Barriers/liners that are deposited onto dielectric materials can includerefractive materials, such as tungsten (W), molybdenum (Mo), andtantalum (Ta), that are non-reactive and immiscible in Cu, and can offerlow electrical resistivity. Current integration schemes that integrateCu metallization and dielectric materials can require barrier/linerdeposition processes at substrate temperatures between about 400° C. andabout 500° C., or lower.

For example, Cu integration schemes for technology nodes less than orequal to 130 nm currently utilize a low dielectric constant (low-k)inter-level dielectric, followed by a physical vapor deposition (PVD)TaN layer and Ta barrier layer, followed by a PVD Cu seed layer, and anelectro-chemical deposition (ECD) Cu fill. Generally, Ta layers arechosen for their adhesion properties (i.e., their ability to adhere onlow-k films), and Ta/TaN layers are generally chosen for their barrierproperties (i.e., their ability to prevent Cu diffusion into the low-kfilm).

As described above, significant effort has been devoted to the study andimplementation of thin transition metal layers as Cu diffusion barriers,these studies including such materials as chromium, tantalum, molybdenumand tungsten. Each of these materials exhibits low miscibility in Cu.More recently, other materials, such as ruthenium (Ru) and rhodium (Rh),have been identified as potential barrier layers since they are expectedto behave similarly to conventional refractory metals. However, the useof Ru or Rh can permit the use of only one barrier layer, as opposed totwo layers, such as Ta/TaN. This observation is due to the adhesive andbarrier properties of these materials. For example, one Ru layer canreplace the Ta/TaN barrier layer. Moreover, current research is findingthat the one Ru layer can further replace the Cu seed layer, and bulk Cufill can proceed directly following Ru deposition. This observation isdue to good adhesion between the Cu and the Ru layers.

Conventionally, Ru layers can be formed by thermally decomposing aruthenium-containing precursor, such as a ruthenium carbonyl precursor,in a thermal chemical vapor deposition (TCVD) process. Materialproperties of Ru layers that are deposited by thermal decomposition ofmetal-carbonyl precursors (e.g., Ru₃(CO)₁₂), can deteriorate when thesubstrate temperature is lowered to below about 400° C. As a result, anincrease in the (electrical) resistivity of the Ru layers and poorsurface morphology (e.g., the formation of nodules) at low depositiontemperatures has been attributed to increased incorporation of COreaction by-products into the thermally deposited Ru layers. Botheffects can be explained by a reduced CO desorption rate from thethermal decomposition of the ruthenium-carbonyl precursor at substratetemperatures below about 400° C.

Additionally, the use of metal-carbonyls, such as ruthenium carbonyl,can lead to poor deposition rates due to their low vapor pressure, andthe transport issues associated therewith. Overall, the inventor hasobserved that current deposition systems suffer from such a low rate,making the deposition of such metal films impractical.

SUMMARY OF THE INVENTION

The present invention provides a method for depositing a Ru metal layeron a patterned substrate from a film precursor vapor delivered from amulti-tray film precursor evaporation system. To this end, the methodcomprises providing a patterned substrate in a process chamber of adeposition system, wherein the patterned substrate contains one or morevias or trenches, or combinations thereof, and forming a process gascontaining Ru₃(CO)₁₂ precursor vapor and a carrier gas comprising COgas. The process gas is formed by: providing a solid Ru₃(CO)₁₂ precursorin a plurality of spaced trays within a precursor evaporation system,wherein each tray is configured to support the solid Ru₃(CO)₁₂ precursorand wherein the plurality of spaced trays collectively provide aplurality of surfaces of solid Ru₃(CO)₁₂ precursor; heating the solidRu₃(CO)₁₂ precursor in the plurality of spaced trays in the precursorevaporation system to a temperature greater than about 60° C. andmaintaining the solid Ru₃(CO)₁₂ precursor at the temperature to form theRu₃(CO)₁₂ precursor vapor; and flowing the carrier gas in contact withthe plurality of surfaces of the solid Ru₃(CO)₁₂ precursor in theprecursor evaporation system during the heating to capture Ru₃(CO)₁₂precursor vapor in the carrier gas as the vapor is being formed at theplurality of surfaces. The method further includes transporting theprocess gas from the precursor evaporation system to the process chamberand exposing the patterned substrate to the process gas to deposit a Rumetal layer on the patterned substrate by a thermal chemical vapordeposition process.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 depicts a schematic view of a deposition system according to anembodiment of the invention;

FIG. 2 depicts a schematic view of a deposition system according toanother embodiment of the invention;

FIG. 3 presents in cross-sectional view a film precursor evaporationsystem according to an embodiment of the invention;

FIG. 4 presents in cross-sectional view a bottom tray for use in a filmprecursor evaporation system according to an embodiment of theinvention;

FIG. 5A presents in cross-sectional view a stackable upper tray for usein a film precursor evaporation system according to an embodiment of theinvention;

FIG. 5B presents in perspective view the tray of FIG. 5A;

FIG. 6 presents in perspective view a film precursor evaporation systemaccording to another embodiment of the invention; and

FIG. 7 illustrates a method of operating a film precursor evaporationsystem of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following description, in order to facilitate a thoroughunderstanding of the invention and for purposes of explanation and notlimitation, specific details are set forth, such as a particulargeometry of the deposition system and descriptions of variouscomponents. However, it should be understood that the invention may bepracticed in other embodiments that depart from these specific details.

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, FIG. 1illustrates a deposition system 1 for depositing a thin film, such as aruthenium (Ru) or a rhenium (Re) metal film, on a substrate according toone embodiment. The deposition system 1 comprises a process chamber 10having a substrate holder 20 configured to support a substrate 25, uponwhich the thin film is formed. The process chamber 10 is coupled to afilm precursor evaporation system 50 via a vapor precursor deliverysystem 40.

The process chamber 10 is further coupled to a vacuum pumping system 38through a duct 36, wherein the pumping system 38 is configured toevacuate the process chamber 10, vapor precursor delivery system 40, andfilm precursor evaporation system 50 to a pressure suitable for formingthe thin film on substrate 25, and suitable for evaporation of a filmprecursor (not shown) in the film precursor evaporation system 50.

Referring still to FIG. 1, the film precursor evaporation system 50 isconfigured to store a film precursor and heat the film precursor to atemperature sufficient for evaporating the film precursor, whileintroducing vapor phase film precursor to the vapor precursor deliverysystem 40. As will be discussed in more detail below with reference toFIGS. 3-6, the film precursor can, for example, comprise a solid filmprecursor. Additionally, for example, the film precursor can include asolid metal precursor. Additionally, for example, the film precursor caninclude a metal-carbonyl. For instance, the metal-carbonyl can includeruthenium carbonyl (Ru₃(CO)₁₂), or rhenium carbonyl (Re₂(CO)₁₀).Additionally, for instance, the metal-carbonyl can include W(CO)₆,Mo(CO)₆, Co₂(CO)₈, Rh₄(CO)₁₂, Cr(CO)₆, or Os₃(CO)₁₂.

In order to achieve the desired temperature for evaporating the filmprecursor (or subliming a solid metal precursor), the film precursorevaporation system 50 is coupled to an evaporation temperature controlsystem 54 configured to control the evaporation temperature. Forinstance, the temperature of the film precursor is generally elevated toapproximately 40 to 45° C. in conventional systems in order to sublime,for example, ruthenium carbonyl. At this temperature, the vapor pressureof the ruthenium carbonyl, for instance, ranges from approximately 1 toapproximately 3 mTorr. As the film precursor is heated to causeevaporation (or sublimation), a carrier gas is passed over the filmprecursor or by the film precursor. The carrier gas can include, forexample, an inert gas, such as a noble gas (i.e., He, Ne, Ar, Kr, Xe),or a monoxide, such as carbon monoxide (CO), for use withmetal-carbonyls, or a mixture thereof. For example, a carrier gas supplysystem 60 is coupled to the film precursor evaporation system 50, and itis configured to, for instance, supply the carrier gas above the filmprecursor via feed line 61. In another example, carrier gas supplysystem 60 is coupled to the vapor precursor delivery system 40 and isconfigured to supply the carrier gas to the vapor of the film precursorvia feed line 63 as or after it enters the vapor precursor deliverysystem 40. Although not shown, the carrier gas supply system 60 cancomprise a gas source, one or more control valves, one or more filters,and a mass flow controller. For instance, the flow rate of carrier gascan range from approximately 5 sccm (standard cubic centimeters perminute) to approximately 1000 sccm. For example, the flow rate ofcarrier gas can range from about 10 sccm to about 200 sccm. By way offurther example, the flow rate of carrier gas can range from about 20sccm to about 100 sccm.

Downstream from the film precursor evaporation system 50, the filmprecursor vapor flows with the carrier gas through the vapor precursordelivery system 40 until it enters a vapor distribution system 30coupled to the process chamber 10. The vapor precursor delivery system40 can be coupled to a vapor line temperature control system 42 in orderto control the vapor line temperature, and prevent decomposition of thefilm precursor vapor as well as condensation of the film precursorvapor. For example, the vapor line temperature can be set to a valueapproximately equal to or greater than the evaporation temperature.Additionally, for example, the vapor precursor delivery system 40 can becharacterized by a high conductance in excess of about 50 liters/second.

Referring again to FIG. 1, the vapor distribution system 30, coupled tothe process chamber 10, comprises a plenum 32 within which the vapordisperses prior to passing through a vapor distribution plate 34 andentering a processing zone 33 above substrate 25. In addition, the vapordistribution plate 34 can be coupled to a distribution plate temperaturecontrol system 35 configured to control the temperature of the vapordistribution plate 34. For example, the temperature of the vapordistribution plate can be set to a value approximately equal to thevapor line temperature. However, it may be less, or it may be greater.

Once film precursor vapor enters the processing zone 33, the filmprecursor vapor thermally decomposes upon adsorption at the substratesurface due to the elevated temperature of the substrate 25, and thethin film is formed on the substrate 25. The substrate holder 20 isconfigured to elevate the temperature of substrate 25, by virtue of thesubstrate holder 20 being coupled to a substrate temperature controlsystem 22. For example, the substrate temperature control system 22 canbe configured to elevate the temperature of substrate 25 up toapproximately 500° C. In one embodiment, the substrate temperature canrange from about 100° C. to about 500° C. In another embodiment, thesubstrate temperature can range from about 300° C. to about 400° C.Additionally, process chamber 10 can be coupled to a chamber temperaturecontrol system 12 configured to control the temperature of the chamberwalls.

As described above, for example, conventional systems have contemplatedoperating the film precursor evaporation system 50, as well as the vaporprecursor delivery system 40, within a temperature range ofapproximately 40 to 45° C. for ruthenium carbonyl in order to limitmetal vapor precursor decomposition, and metal vapor precursorcondensation. For example, ruthenium carbonyl precursor can decompose atelevated temperatures to form by-products, such as those illustratedbelow:Ru₃(CO)₁₂*(ad)

Ru₃(CO)_(x)*(ad)+(12−x)CO(g)  (1)or,Ru₃(CO)_(x)*(ad)

3Ru(s)+xCO(g)  (2)wherein these by-products can adsorb, i.e., condense, on the interiorsurfaces of the deposition system 1. The accumulation of material onthese surfaces can cause problems from one substrate to the next, suchas process repeatability. Alternatively, for example, ruthenium carbonylprecursor can condense at depressed temperatures to causerecrystallization, viz.Ru₃(CO)₁₂(g)

Ru₃(CO)₁₂*(ad)  (3)

However, within such systems having a small process window, thedeposition rate becomes extremely low, due in part to the low vaporpressure of ruthenium carbonyl. For instance, the deposition rate can beas low as approximately 1 Angstrom per minute. Therefore, according toone embodiment, the evaporation temperature is elevated to be greaterthan or equal to approximately 40° C. Alternatively, the evaporationtemperature is elevated to be greater than or equal to approximately 50°C. In an exemplary embodiment of the present invention, the evaporationtemperature is elevated to be greater than or equal to approximately 60°C. In a further exemplary embodiment, the evaporation temperature iselevated to range from approximately 60 to 100° C., and for example fromapproximately 60 to 90° C. The elevated temperature increases theevaporation rate due to the higher vapor pressure (e.g., nearly an orderof magnitude larger) and, hence, it is expected by the inventors toincrease the deposition rate. It may also be desirable to periodicallyclean deposition system 1 following processing of one or moresubstrates. For example, additional details on a cleaning method andsystem can be obtained from co-pending U.S. patent application Ser. No.10/998,394, filed on even date herewith and entitled “Method and Systemfor Performing In-situ Cleaning of a Deposition System”, which is hereinincorporated by reference in its entirety.

As discussed above, the deposition rate is proportional to the amount offilm precursor that is evaporated and transported to the substrate priorto decomposition, or condensation, or both. Therefore, in order toachieve a desired deposition rate, and to maintain consistent processingperformance (i.e., deposition rate, film thickness, film uniformity,film morphology, etc.) from one substrate to the next, it is importantto provide the ability to monitor, adjust, or control the flow rate ofthe film precursor vapor. In conventional systems, an operator mayindirectly determine the flow rate of film precursor vapor by using theevaporation temperature, and a pre-determined relationship between theevaporation temperature and the flow rate. However, processes and theirperformance drift in time, and hence it is imperative that the flow rateis measured more accurately. For example, additional details can beobtained from co-pending U.S. patent application Ser. No. 10/998,393,filed on even date herewith and entitled “Method and System forMeasuring a Flow Rate in a Solid Precursor Delivery System”, which isherein incorporated by reference in its entirety.

Still referring the FIG. 1, the deposition system 1 can further includea control system 80 configured to operate, and control the operation ofthe deposition system 1. The control system 80 is coupled to the processchamber 10, the substrate holder 20, the substrate temperature controlsystem 22, the chamber temperature control system 12, the vapordistribution system 30, the vapor precursor delivery system 40, the filmprecursor evaporation system 50, and the carrier gas supply system 60.

In yet another embodiment, FIG. 2 illustrates a deposition system 100for depositing a thin film, such as a ruthenium (Ru) or a rhenium (Re)metal film, on a substrate. The deposition system 100 comprises aprocess chamber having a substrate holder 120 configured to support asubstrate 125, upon which the thin film is formed. The process chamber110 is coupled to a precursor delivery system 105 having film precursorevaporation system 150 configured to store and evaporate a filmprecursor (not shown), and a vapor precursor delivery system 140configured to transport film precursor vapor.

The process chamber 110 comprises an upper chamber section 111, a lowerchamber section 112, and an exhaust chamber 113. An opening 114 isformed within lower chamber section 112, where bottom section 112couples with exhaust chamber 113.

Referring still to FIG. 2, substrate holder 120 provides a horizontalsurface to support substrate (or wafer) 125, which is to be processed.The substrate holder 120 can be supported by a cylindrical supportmember 122, which extends upward from the lower portion of exhaustchamber 113. An optional guide ring 124 for positioning the substrate125 on the substrate holder 120 is provided on the edge of substrateholder 120. Furthermore, the substrate holder 120 comprises a heater 126coupled to substrate holder temperature control system 128. The heater126 can, for example, include one or more resistive heating elements.Alternately, the heater 126 can, for example, include a radiant heatingsystem, such as a tungsten-halogen lamp. The substrate holdertemperature control system 128 can include a power source for providingpower to the one or more heating elements, one or more temperaturesensors for measuring the substrate temperature, or the substrate holdertemperature, or both, and a controller configured to perform at leastone of monitoring, adjusting, or controlling the temperature of thesubstrate or substrate holder.

During processing, the heated substrate 125 can thermally decompose thevapor of film precursor vapor, such as a metal-carbonyl precursor, andenable deposition of a thin film, such as a metal layer, on thesubstrate 125. According to one embodiment, the film precursor includesa solid precursor. According to another embodiment, the film precursorincludes a metal precursor. According to another embodiment, the filmprecursor includes a solid metal precursor. According to yet anotherembodiment, the film precursor includes a metal-carbonyl precursor.According to yet another embodiment, the film precursor can be aruthenium-carbonyl precursor, for example Ru₃(CO)₁₂. According to yetanother embodiment of the invention, the film precursor can be a rheniumcarbonyl precursor, for example Re₂(CO)₁₀. As will be appreciated bythose skilled in the art of thermal chemical vapor deposition, otherruthenium carbonyl precursors and rhenium carbonyl precursors can beused without departing from the scope of the invention. In yet anotherembodiment, the film precursor can be W(CO)₆, Mo(CO)₆, Co₂(CO)₈,Rh₄(CO)₁₂, Cr(CO)₆, or Os₃(CO)₁₂. The substrate holder 120 is heated toa pre-determined temperature that is suitable for depositing, forinstance, a desired Ru, Re, or other metal layer onto the substrate 125.Additionally, a heater (not shown), coupled to a chamber temperaturecontrol system 121, can be embedded in the walls of process chamber 110to heat the chamber walls to a pre-determined temperature. The heatercan maintain the temperature of the walls of process chamber 110 fromabout 40° C. to about 100° C., for example from about 40° C. to about80° C. A pressure gauge (not shown) is used to measure the processchamber pressure.

Also shown in FIG. 2, a vapor distribution system 130 is coupled to theupper chamber section 111 of process chamber 110. Vapor distributionsystem 130 comprises a vapor distribution plate 131 configured tointroduce precursor vapor from vapor distribution plenum 132 to aprocessing zone 133 above substrate 125 through one or more orifices134.

Furthermore, an opening 135 is provided in the upper chamber section 111for introducing a vapor precursor from vapor precursor delivery system140 into vapor distribution plenum 132. Moreover, temperature controlelements 136, such as concentric fluid channels configured to flow acooled or heated fluid, are provided for controlling the temperature ofthe vapor distribution system 130, and thereby prevent the decompositionof the film precursor inside the vapor distribution system 130. Forinstance, a fluid, such as water, can be supplied to the fluid channelsfrom a vapor distribution temperature control system 138. The vapordistribution temperature control system 138 can include a fluid source,a heat exchanger, one or more temperature sensors for measuring thefluid temperature or vapor distribution plate temperature or both, and acontroller configured to control the temperature of the vapordistribution plate 131 from about 20° C. to about 100° C.

Film precursor evaporation system 150 is configured to hold a filmprecursor, and evaporate (or sublime) the film precursor by elevatingthe temperature of the film precursor. A precursor heater 154 isprovided for heating the film precursor to maintain the film precursorat a temperature that produces a desired vapor pressure of filmprecursor. The precursor heater 154 is coupled to an evaporationtemperature control system 156 configured to control the temperature ofthe film precursor. For example, the precursor heater 154 can beconfigured to adjust the temperature of the film precursor (orevaporation temperature) to be greater than or equal to approximately40° C. Alternatively, the evaporation temperature is elevated to begreater than or equal to approximately 50° C. For example, theevaporation temperature is elevated to be greater than or equal toapproximately 60° C. In one embodiment, the evaporation temperature iselevated to range from approximately 60 to 100° C., and in anotherembodiment, to range from approximately 60 to 90° C.

As the film precursor is heated to cause evaporation (or sublimation), acarrier gas can be passed over the film precursor, or by the filmprecursor. The carrier gas can include, for example, an inert gas, suchas a noble gas (i.e., He, Ne, Ar, Kr, Xe), or a monoxide, such as carbonmonoxide (CO), for use with metal-carbonyls, or a mixture thereof. Forexample, a carrier gas supply system 160 is coupled to the filmprecursor evaporation system 150, and it is configured to, for instance,supply the carrier gas above the film precursor. Although not shown inFIG. 2, carrier gas supply system 160 can also be coupled to the vaporprecursor delivery system 140 to supply the carrier gas to the vapor ofthe film precursor as or after it enters the vapor precursor deliverysystem 140. The carrier gas supply system 160 can comprise a gas source161, one or more control valves 162, one or more filters 164, and a massflow controller 165. For instance, the flow rate of carrier gas canrange from approximately 5 sccm (standard cubic centimeters per minute)to approximately 1000 sccm. In one embodiment, for instance, the flowrate of carrier gas can range from about 10 sccm to about 200 sccm. Inanother embodiment, for instance, the flow rate of carrier gas can rangefrom about 20 sccm to about 100 sccm.

Additionally, a sensor 166 is provided for measuring the total gas flowfrom the film precursor evaporation system 150. The sensor 166 can, forexample, comprise a mass flow controller, and the amount of filmprecursor delivered to the process chamber 110, can be determined usingsensor 166 and mass flow controller 165. Alternately, the sensor 166 cancomprise a light absorption sensor to measure the concentration of thefilm precursor in the gas flow to the process chamber 110.

A bypass line 167 can be located downstream from sensor 166, and it canconnect the vapor delivery system 140 to an exhaust line 116. Bypassline 167 is provided for evacuating the vapor precursor delivery system140, and for stabilizing the supply of the film precursor to the processchamber 110. In addition, a bypass valve 168, located downstream fromthe branching of the vapor precursor delivery system 140, is provided onbypass line 167.

Referring still to FIG. 2, the vapor precursor delivery system 140comprises a high conductance vapor line having first and second valves141 and 142 respectively. Additionally, the vapor precursor deliverysystem 140 can further comprise a vapor line temperature control system143 configured to heat the vapor precursor delivery system 140 viaheaters (not shown). The temperatures of the vapor lines can becontrolled to avoid condensation of the film precursor in the vaporline. The temperature of the vapor lines can be controlled from about20° C. to about 100° C., or from about 40° C. to about 90° C. Forexample, the vapor line temperature can be set to a value approximatelyequal to or greater than the evaporation temperature.

Moreover, dilution gases can be supplied from a dilution gas supplysystem 190. The dilution gas can include, for example, an inert gas,such as a noble gas (i.e., He, Ne, Ar, Kr, Xe), or a monoxide, such ascarbon monoxide (CO), for use with metal-carbonyls, or a mixturethereof. For example, the dilution gas supply system 190 is coupled tothe vapor precursor delivery system 140, and it is configured to, forinstance, supply the dilution gas to vapor film precursor. The dilutiongas supply system 190 can comprise a gas source 191, one or more controlvalves 192, one or more filters 194, and a mass flow controller 195. Forinstance, the flow rate of carrier gas can range from approximately 5sccm (standard cubic centimeters per minute) to approximately 1000 sccm.

Mass flow controllers 165 and 195, and valves 162, 192, 168, 141, and142 are controlled by controller 196, which controls the supply,shutoff, and the flow of the carrier gas, the film precursor vapor, andthe dilution gas. Sensor 166 is also connected to controller 196 and,based on output of the sensor 166, controller 196 can control thecarrier gas flow through mass flow controller 165 to obtain the desiredfilm precursor flow to the process chamber 110.

As illustrated in FIG. 2, the exhaust line 116 connects exhaust chamber113 to pumping system 118. A vacuum pump 119 is used to evacuate processchamber 110 to the desired degree of vacuum, and to remove gaseousspecies from the process chamber 110 during processing. An automaticpressure controller (APC) 115 and a trap 117 can be used in series withthe vacuum pump 119. The vacuum pump 119 can include a turbo-molecularpump (TMP) capable of a pumping seed up to 5000 liters per second (andgreater). Alternately, the vacuum pump 119 can include a dry roughingpump. During processing, the carrier gas, dilution gas, or filmprecursor vapor, or any combination thereof, can be introduced into theprocess chamber 110, and the chamber pressure can be adjusted by the APC115. For example, the chamber pressure can range from approximately 1mTorr to approximately 500 mTorr, and in a further example, the chamberpressure can range from about 5 mTorr to 50 mTorr. The APC 115 cancomprise a butterfly-type valve, or a gate valve. The trap 117 cancollect unreacted precursor material, and by-products from the processchamber 110.

Referring back to the substrate holder 120 in the process chamber 110,as shown in FIG. 2, three substrate lift pins 127 (only two are shown)are provided for holding, raising, and lowering the substrate 125. Thesubstrate lift pins 127 are coupled to plate 123, and can be lowered tobelow the upper surface of substrate holder 120. A drive mechanism 129utilizing, for example, an air cylinder, provides means for raising andlowering the plate 123. Substrate 125 can be transferred into and out ofprocess chamber 110 through gate valve 200, and chamber feed-throughpassage 202 via a robotic transfer system (not shown), and received bythe substrate lift pins 127. Once the substrate 125 is received from thetransfer system, it can be lowered to the upper surface of the substrateholder 120 by lowering the substrate lift pins 127.

Referring again to FIG. 2, a controller 180 includes a microprocessor, amemory, and a digital I/O port capable of generating control voltagessufficient to communicate and activate inputs of the processing system100 as well as monitor outputs from the processing system 100. Moreover,the processing system controller 180 is coupled to and exchangesinformation with process chamber 110; precursor delivery system 105,which includes controller 196, vapor line temperature control system142, and evaporation temperature control system 156; vapor distributiontemperature control system 138; vacuum pumping system 118; and substrateholder temperature control system 128. In the vacuum pumping system 118,the controller 180 is coupled to and exchanges information with theautomatic pressure controller 115 for controlling the pressure in theprocess chamber 110. A program stored in the memory is utilized tocontrol the aforementioned components of deposition system 100 accordingto a stored process recipe. One example of processing system controller180 is a DELL PRECISION WORKSTATION 610™, available from DellCorporation, Dallas, Tex. The controller 180 may also be implemented asa general-purpose computer, digital signal process, etc.

Controller 180 may be locally located relative to the deposition system100, or it may be remotely located relative to the deposition system 100via an internet or intranet. Thus, controller 180 can exchange data withthe deposition system 100 using at least one of a direct connection, anintranet, or the internet. Controller 180 may be coupled to an intranetat a customer site (i.e., a device maker, etc.), or coupled to anintranet at a vendor site (i.e., an equipment manufacturer).Furthermore, another computer (i.e., controller, server, etc.) canaccess controller 180 to exchange data via at least one of a directconnection, an intranet, or the internet.

Referring now to FIG. 3, a film precursor evaporation system 300 isdepicted in cross-sectional view according to an embodiment. The filmprecursor evaporation system 300 comprises a container 310 having anouter wall 312 and a bottom 314. Additionally, the film precursorevaporation system 300 comprises a lid 320 configured to be sealablycoupled to the container 310, wherein the lid 320 includes an outlet 322configured to be sealably coupled to a thin film deposition system, suchas the one depicted in FIG. 1 or 2. The container 310 and lid 320 form asealed environment when coupled to the thin film deposition system. Thecontainer 310 and lid 320 can, for example, be fabricated from A6061aluminum, and may or may not include a coating applied thereon.

Furthermore, the container 310 is configured to be coupled to a heater(not shown) in order to elevate the evaporation temperature of the filmprecursor evaporation system 300, and to a temperature control system(not shown) in order to perform at least one of monitoring, adjusting,or controlling the evaporation temperature. When the evaporationtemperature is elevated to an appropriate value as described earlier,film precursor evaporates (or sublimes) forming film precursor vapor tobe transported through the vapor delivery system to the thin filmdeposition system. The container 310 is also sealably coupled to acarrier gas supply system (not shown), wherein container 310 isconfigured to receive a carrier gas for transporting the film precursorvapor.

Referring still to FIG. 3, and also to FIG. 4, the film precursorevaporation system 300 further comprises a base tray 330 configured torest on the bottom 314 of the container 310, and having a base outerwall 332 configured to retain the film precursor 350 on the base tray330. The base outer wall 332 includes a base support edge 333 forsupporting upper trays thereon, as discussed below. Furthermore, thebase outer wall 332 includes one or more base tray openings 334configured to flow the carrier gas from the carrier gas supply system(not shown), over the film precursor 350 towards a center of thecontainer 310, and along a central flow channel 318 to exhaust throughthe outlet 322 in the lid 320 with film precursor vapor. Consequently,the film precursor level in the base tray 330 should be below theposition of the base tray openings 334.

Referring still to FIG. 3, and also to FIGS. 5A and 5B, the filmprecursor evaporation system 300 further comprises one or more stackableupper trays 340 configured to support the film precursor 350, andconfigured to be positioned or stacked upon at least one of the basetray 330 or another of the stackable upper trays 340. Each of thestackable upper trays 340 comprises an upper outer wall 342 and an innerwall 344 configured to retain the film precursor 350 therebetween. Theinner walls 344 define the central flow channel 318. The upper outerwall 342 further includes an upper support edge 343 for supporting anadditional upper tray 340. Thus, a first upper tray 340 is positioned tobe supported on base support edge 333 of base tray 330, and if desired,one or more additional upper trays may be positioned to be supported onthe upper support edge 343 of a preceding upper tray 340. The upperouter wall 342 of each upper tray 340 includes one or more upper trayopenings 346 configured to flow the carrier gas from the carrier gassupply system (not shown), over the film precursor 350 towards centralflow channel 318 of the container 310, and exhaust through the outlet322 in the lid 320 with film precursor vapor. Consequently, inner walls344 should be shorter than upper outer walls 342 to allow the carriergas to flow substantially radially to the central flow channel 318.Additionally, the film precursor level in each upper tray 340 should beat or below the height of the inner walls 342, and below the position ofthe upper tray openings 346.

The base tray 330 and the stackable upper trays 340 are depicted to becylindrical in shape. However, the shape can vary. For instance, theshape of the trays can be rectangular, square or oval. Similarly, theinner walls 344, and thus central upper flow channel 318, can bedifferently shaped.

When one or more stackable upper trays 340 are stacked upon the basetray 330, a stack 370 is formed, which provides for an annular space 360between the base outer wall 332 of the base tray 330 and the containerouter wall 312, and between the upper outer walls 342 of the one or morestackable upper trays 340 and the container outer wall 312. Thecontainer 310 can further comprise one or more spacers (not shown)configured to space the base outer wall 332 of the base tray 330 and theupper outer walls 342 of the one or more stackable upper trays 340 fromthe container outer wall 312, and thereby ensure equal spacing withinthe annular space 360. To state it another way, in one embodiment, thecontainer 310 is configured such that the base outer wall 332 and theupper outer walls 342 are in vertical alignment.

The number of trays, including both the base tray and the stackableupper trays, can range from two (2) to twenty (20) and, for example inone embodiment, the number of trays can be five (5), as shown in FIG. 3.In an exemplary embodiment, the stack 370 includes a base tray 330 andat least one upper tray 340 supported by the base tray 330. The basetray 330 may be as shown in FIGS. 3 and 4, or may have the sameconfiguration as the upper trays 340 as they are shown in FIGS. 3-5B. Inother words, the base tray 330 may have an inner wall. Although, inFIGS. 3-5B, the stack 370 is shown to comprise a base tray 330 with oneor more separatable and stackable upper trays 340, a system 300′ mayinclude a container 310′ with a stack 370′ that comprises a singleunitary piece having a base tray 330 integral with one or more uppertrays 340, as shown in FIG. 6, such that the base outer wall 332 andupper outer walls 342 are integral. Integral is understood to include amonolithic structure, such as an integrally molded structure having nodiscernible boundaries between trays, as well as a permanentlyadhesively or mechanically joined structure where there is permanentjoinder between the trays. Separatable is understood to include nojoinder between trays or temporary joinder, whether adhesive ormechanical.

The base tray 330 and each of the upper trays 340, whether stackable orintegral, are configured to support a film precursor 350. According toone embodiment, the film precursor 350 includes a solid precursor.According to another embodiment, the film precursor 350 includes aliquid precursor. According to another embodiment, the film precursor350 includes a metal precursor. According to another embodiment, thefilm precursor 350 includes a solid metal precursor. According to yetanother embodiment, the film precursor 350 includes a metal-carbonylprecursor. According to yet another embodiment, the film precursor 350can be a ruthenium-carbonyl precursor, for example Ru₃(CO)₁₂. Accordingto yet another embodiment of the invention, the film precursor 350 canbe a rhenium carbonyl precursor, for example Re₂(CO)₁₀. In yet anotherembodiment, the film precursor 350 can be W(CO)₆, Mo(CO)₆, Co₂(CO)₈,Rh₄(CO)₁₂, Cr(CO)₆, or Os₃(CO)₁₂.

As described above, the film precursor 350 can include a solidprecursor. The solid precursor can take the form of a solid powder, orit may take the form of one or more solid tablets. For example, the oneor more solid tablets can be prepared by a number of processes,including a sintering process, a stamping process, a dipping process, ora spin-on process, or any combination thereof. Additionally, the solidprecursor in solid tablet form may or may not adhere to the base tray330 or upper tray 340. For example, a refractory metal powder may besintered in a sintering furnace configured for both vacuum and inert gasatmospheres, and temperature up to 2000° C. and 2500° C. Alternatively,for example, a refractory metal powder can be dispersed in a fluidmedium, dispensed on a tray, and distributed evenly over the traysurfaces using a spin coating process. The refractory metal spin coatmay then be thermally cured.

As described earlier, carrier gas is supplied to the container 310 froma carrier gas supply system (not shown). As shown in FIGS. 3 and 6, thecarrier gas may be coupled to the container 310 through the lid 320 viaa gas supply line (not shown) sealably coupled to the lid 320. The gassupply line feeds a gas channel 380 that extends downward through theouter wall 312 of container 310, passes through the bottom 314 ofcontainer 310 and opens to the annular space 360.

Referring again to FIG. 3, the inner diameter of the container outerwall 312 can, for example, range from approximately 10 cm toapproximately 100 cm and, for example, can range from approximately 15cm to approximately 40 cm. For instance, the inner diameter of outerwall 312 can be 20 cm. The diameter of the outlet 322 and the innerdiameter of the inner walls 344 of the upper trays 340 can, for example,range from approximately 1 cm to 30 cm and, additionally, for example,the outlet diameter and inner wall diameter can range from approximately5 to approximately 20 cm. For instance, the outlet diameter can be 10cm. Additionally, the outer diameter of the base tray 330 and each ofthe upper trays 340 can range from approximately 75% to approximately99% of the inner diameter of the outer wall 312 of container 310 and,for example, the tray diameter can range from approximately 85% to 99%of the inner diameter of the outer wall 312 of container 310. Forinstance, the tray diameter can be 19.75 cm. Additionally, the height ofthe base outer wall 332 of base tray 330 and of the upper outer wall 342of each of the upper trays 340 can range from approximately 5 mm toapproximately 50 mm and, for example, the height of each isapproximately 30 mm. In addition, the height of each inner wall 344 canrange from approximately 10% to approximately 90% of the height of theupper outer wall 342. For example, the height of each inner wall canrange from approximately 2 mm to approximately 45 mm and, for example,is approximately 20 mm.

Referring yet again to FIG. 3, the one or more base tray openings 334and the one or more upper tray openings 346 can include one or moreslots. Alternatively, the one or more base tray openings 334 and the oneor more upper tray openings 346 can include one or more orifices. Thediameter of each orifice can, for example, range from approximately 0.4mm to approximately 2 mm. For example, the diameter of each orifice canbe approximately 1 mm. In one embodiment, the orifice diameter and widthof annular space 360 are chosen such that the conductance throughannular space 360 is sufficiently larger than the net conductance of theorifices in order to maintain substantially uniform distribution of thecarrier gas throughout the annular space 360. The number of orificescan, for example, range from approximately 2 to approximately 1000orifices and, by way of further example, can range from approximately 50to approximately 100 orifices. For instance, the one or more base trayopenings 334 can include seventy two (72), orifices of 1 mm diameter,and the one or more stackable tray openings 346 can include seventy two(72) orifices of 1 mm diameter, wherein the width of the annular space360 is approximately 2.65 mm.

The film precursor evaporation system 300 or 300′ may be used as eitherfilm precursor evaporation system 50 in FIG. 1, or film precursorevaporation system 150 in FIG. 2. Alternatively, system 300 or 300′ maybe used in any film deposition system suitable for depositing a thinfilm on a substrate from precursor vapor.

Referring now to FIG. 7, a method of depositing a thin film on asubstrate is described. A flow chart 700 is used to illustrate the stepsin depositing the thin film in a deposition system of the presentinvention. The thin film deposition begins in 710 with placing asubstrate in the deposition system in succession for forming the thinfilm on the substrate. For example, the deposition system can includeany one of the depositions systems described above in FIGS. 1 and 2. Thedeposition system can include a process chamber for facilitating thedeposition process, and a substrate holder coupled to the processchamber and configured to support the substrate. Then, in 720, a filmprecursor is introduced to the deposition system. For instance, the filmprecursor is introduced to a film precursor evaporation system coupledto the process chamber via a precursor vapor delivery system.Additionally, for instance, the precursor vapor delivery system can beheated.

In 730, the film precursor is heated to form a film precursor vapor. Thefilm precursor vapor can then be transported to the process chamberthrough the precursor vapor delivery system. In 740, the substrate isheated to a substrate temperature sufficient to decompose the filmprecursor vapor, and, in 750, the substrate is exposed to the filmprecursor vapor. Steps 710 to 750 may be repeated successively a desirednumber of times to deposit a metal film on a desired number ofsubstrates.

Following the deposition of the thin film on one or more substrates, thestack of trays 370 or 370′, or one or more of the base or upper trays330, 340, can be periodically replaced in 760 in order to replenish thelevel of film precursor 350 in each tray.

Although only certain exemplary embodiments of this invention have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention.

1. A method of depositing a Ru metal layer on a patterned substrate,comprising: providing a patterned substrate in a process chamber of adeposition system, wherein the patterned substrate contains one or morevias or trenches, or combinations thereof; forming a process gascontaining Ru₃(CO)₁₂ precursor vapor and a carrier gas comprising CO gasby: providing a solid Ru₃(CO)₁₂ precursor in a plurality of spaced trayswithin a precursor evaporation system, wherein each tray in theplurality of spaced trays is configured to support the solid Ru₃(CO)₁₂precursor and wherein the plurality of spaced trays collectively providea plurality of surfaces of solid Ru₃(CO)₁₂ precursor; heating the solidRu₃(CO)₁₂ precursor in the plurality of spaced trays in the precursorevaporation system to a temperature greater than about 60° C. andmaintaining the solid Ru₃(CO)₁₂ precursor at the temperature to form theRu₃(CO)₁₂ precursor vapor; and flowing the carrier gas in contact withthe plurality of surfaces of the solid Ru₃(CO)₁₂ precursor in theprecursor evaporation system during the heating to capture Ru₃(CO)₁₂precursor vapor in the carrier gas as the vapor is being formed at theplurality of surfaces; transporting the process gas from the precursorevaporation system to the process chamber; and exposing the patternedsubstrate to the process gas to deposit a Ru metal layer on thepatterned substrate by a thermal chemical vapor deposition process. 2.The method of claim 1, wherein a flow of the CO gas is between about 5sccm and about 1000 sccm.
 3. The method of claim 1, wherein a flow ofthe CO gas is between about 10 sccm and about 200 sccm.
 4. The method ofclaim 1, wherein the forming further comprises: flowing a dilution gasover or through the Ru₃(CO)₁₂ precursor.
 5. The method of claim 4,wherein the dilution gas comprises a noble gas.
 6. The method of claim4, wherein the flow of the dilution gas is between about 5 sccm andabout 1000 sccm.
 7. The method of claim 1, further comprising:maintaining the substrate at a temperature between about 50° C. andabout 500° C. during the exposing.
 8. The method of claim 1, furthercomprising: maintaining the substrate at a temperature between about300° C. and about 400° C. during the exposing.
 9. The method of claim 1,further comprising: maintaining the process chamber at a pressurebetween about 1 mTorr and about 500 mTorr during the exposing.
 10. Themethod of claim 1, further comprising: maintaining the process chamberat a pressure between about 5 mTorr and about 50 mTorr during theexposing.
 11. The method of claim 1, wherein said heating is to atemperature between about 60° C. and about 90° C.
 12. The method ofclaim 1, wherein said flowing the carrier gas in contact with theplurality of surfaces of the solid Ru₃(CO)₁₂ precursor in the precursorevaporation system comprises: forming a tray stack from the plurality ofspaced trays; flowing the carrier gas comprising the CO gas into theprecursor evaporation system through an inlet sealably coupled to acarrier gas supply system and into a carrier gas supply space configuredto receive a flow of the carrier gas through the inlet; flowing thecarrier gas from the carrier gas supply space through one or moreorifices in each of the plurality of spaced trays such that a portion ofthe flow of the carrier gas flows in contact with each surface of theplurality of surfaces provided by each tray in the plurality of spacedtrays; and collecting each of the portions of the flow of carrier gaswith the precursor vapor in a high conductance evaporation space; andflowing the collected portions of the flow of carrier gas with precursorvapor through an outlet in the precursor evaporation system that issealably coupled to the process chamber.